Re: Calendar hack: Displaying ISO weeks, update for emacs 22, the real update

[Edward M. Reingold]

>>>>> "AH" == Alf-Ivar Holm <address@hidden> writes:

    AH> (defun local-holiday-easter-etc () "List of dates related to Easter in
    AH> Norway, as visible in calendar window."  (if (and (> displayed-month
    AH> 5)) nil;; Ash Wednesday, Good Friday, and Easter are not visible.

This a good example of why the wider window can cause erroneous results.
The test

   (if (> displayed-month 5)

checks if the center of the 3 month window is beyond May, in which case (as
the comment from my code says!) Ash Wednesday, Good Friday, and Easter cannot
be visibible because they occur in Feb/Mar/Apr.  But if the window is 5 months
wide, they could be visible and the command to list or highlight all holidays
will miss them.

Almost all of the non-trivial holidays/diary entries would suffer in the same
way, so rewriting the code properly to display a wider window means modifying
almost every holiday/diary function in some (usually non-obvious) way.
-- 

Professor Edward M. Reingold                Email: address@hidden
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